Radiotherapy planning device and radiotherapy planning method

Abstract

Reduce harmful events to normal tissues in radiotherapy. A radiotherapy planning device of an embodiment includes a processing circuit. The processing circuit sets radiation irradiation conditions for a medical image related to a patient. The processing circuit obtains a histogram of the radiation dose rate in a predetermined area of ​​the patient based on the irradiation conditions. The processing circuit evaluates the irradiation conditions based on the histogram. The processing circuit outputs information based on the evaluation result of the irradiation conditions.

Description

[0001] Reference to related applications

[0002] This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2021-021690 filed on February 15, 2021, and Japanese Patent Application No. 2022-020612 filed on February 14, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention generally relate to a radiation therapy planning device, a radiation therapy planning method, and a radiation therapy assisting device Background Art

[0004] In radiotherapy, there is an ultra-high dose rate short-time irradiation method called FLASH irradiation. FLASH irradiation is a method of selectively damaging tumors without damaging normal tissues by irradiating ultra-high dose rates (e.g., 40 Gy / sec or more) of radiation in a short time (e.g., less than 1 sec). However, in the penumbra generated by the aperture that limits the irradiation field, the dose rate is reduced, so when the penumbra is irradiated to normal tissues, the effect of FLASH irradiation cannot be obtained, and there is a possibility of causing damage to normal tissues.

[0005] [Prior art literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2010-220659 Summary of the invention

[0007] One of the technical problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce harmful events to normal tissues during radiotherapy. However, the technical problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above technical problems. Technical problems corresponding to the effects brought about by the various structures shown in the embodiments described later can also be positioned as other technical problems.

[0008] The radiation therapy planning device of the embodiment has a processing circuit. The processing circuit sets radiation irradiation conditions for a medical image related to a patient. The processing circuit obtains a histogram of the radiation dose rate in a predetermined area of ​​the patient based on the irradiation conditions. The processing circuit evaluates the irradiation conditions based on the histogram. The processing circuit outputs information based on the evaluation result of the irradiation conditions.

[0009] Effects of the Invention

[0010] The object of the invention is to reduce harmful events to normal tissues during radiation therapy. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1It is a diagram showing a configuration example of a radiation therapy system according to the first embodiment.

[0012] Figure 2 It is a diagram showing a configuration example of a radiation therapy planning apparatus according to the first embodiment.

[0013] Figure 3 This is a diagram showing a typical flow of treatment planning processing by a radiation therapy planning apparatus.

[0014] Figure 4 It is a diagram schematically showing the FLASH area and the normal irradiation area when the irradiation direction is "270 degrees" in a cross section parallel to the beam axis of radiation.

[0015] Figure 5 It is a diagram schematically showing the FLASH area and the normal irradiation area when the irradiation direction is "270 degrees" in a cross section perpendicular to the beam axis of radiation.

[0016] Figure 6 This is a diagram showing the normal irradiation volume ratio.

[0017] Figure 7 This is a diagram showing an example of a display screen showing a normal irradiation volume ratio and a determination result.

[0018] Figure 8 It is a diagram schematically showing the process of changing the irradiation conditions.

[0019] Fig. 9 It is a diagram showing an example of a display screen of a normal irradiation volume ratio and a determination result under irradiation conditions after a change.

[0020] Fig.10 It is a diagram showing a display example of the DVH of the FLASH area and the DVH of the normal irradiation area.

[0021] Fig.11 It is a diagram showing a configuration example of a radiation therapy assisting device according to a second embodiment.

[0022] Fig.12 This is a diagram showing a typical flow of treatment support processing by a radiotherapy support device.

[0023] Fig.13 It is a diagram schematically showing a series of processes related to obtaining DrVH at the current position and DrVH at the reference position.

[0024] Fig.14 It is a diagram showing an example of a display screen of DrVH at the current position and DrVH at the reference position.

[0025] Fig.15 This is a diagram showing an example of a warning screen.

[0026] Fig.16 It is a diagram showing a projection example of a correction direction and a correction amount.

[0027] [Explanation of Reference Numerals]

[0028] 1 Radiotherapy system

[0029] 2 Medical image diagnostic equipment

[0030] 3 Radiotherapy planning device

[0031] 4 Radiotherapy equipment

[0032] 5 Radiotherapy assistive devices

[0033] 31 Processing circuit

[0034] 32 Storage Devices

[0035] 33 Display Devices

[0036] 34 Input Devices

[0037] 35 Communication equipment

[0038] 41 beds

[0039] 51 Processing circuit

[0040] 52 Storage Devices

[0041] 53 Display devices

[0042] 54 Input Devices

[0043] 55 Communication equipment

[0044] 311 Get Function

[0045] 312 Condition setting function

[0046] 313 Region determination function

[0047] 314 Calculation function

[0048] 315 Judgment function

[0049] 316 Display control function

[0050] 511 Get Function

[0051] 512 Calculation functions

[0052] 513 Distribution display function

[0053] 514 Determination function

[0054] 515 Warning function DETAILED DESCRIPTION

[0055] The radiation therapy planning device of the embodiment has a processing circuit. The processing circuit sets radiation irradiation conditions for a medical image related to a patient. The processing circuit obtains a histogram of the radiation dose rate in a predetermined area of ​​the patient based on the irradiation conditions. The processing circuit evaluates the irradiation conditions based on the histogram. The processing circuit outputs information based on the evaluation result of the irradiation conditions.

[0056] Hereinafter, embodiments of a radiation therapy planning device and a radiation therapy assisting device will be described in detail with reference to the accompanying drawings.

[0057] The radiation therapy planning device and the radiation therapy supporting device according to the present embodiment are included in the radiation therapy system.

[0058] Figure 1 FIG. 1 is a diagram showing a configuration example of a radiation therapy system 1 according to the present embodiment. Figure 1 As shown, the radiotherapy system 1 includes a medical image diagnosis apparatus 2, a radiotherapy planning apparatus 3, a radiotherapy apparatus 4, and a radiotherapy auxiliary apparatus 5. The medical image diagnosis apparatus 2, the radiotherapy planning apparatus 3, the radiotherapy apparatus 4, and the radiotherapy auxiliary apparatus 5 are connected to each other via a network so as to be able to communicate with each other. The radiotherapy system 1 is a system for formulating a treatment plan related to radiotherapy of a patient and performing radiotherapy according to the treatment plan.

[0059] The medical image diagnostic device 2 performs medical imaging on the patient to be treated, and generates a medical image used in the treatment plan. The medical image can be a two-dimensional image composed of pixels arranged in a two-dimensional shape, or a three-dimensional image composed of voxels arranged in a three-dimensional shape. The medical image diagnostic device 2 can be any medical modality device that can generate medical images. Examples of medical modality devices include X-ray computed tomography devices, magnetic resonance imaging devices, cone beam CT devices, nuclear medicine diagnostic devices, etc. The data of the medical image is sent to the radiation therapy planning device 3, for example.

[0060] The radiotherapy planning device 3 is a computer that creates a treatment plan for a patient using the medical images generated by the medical image diagnosis device 2. The treatment plan data is supplied to the radiotherapy device 4 and the radiotherapy support device 5.

[0061] The radiotherapy device 4 treats the patient by irradiating the patient with radiation according to the treatment plan prepared by the radiotherapy planning device 3. The radiotherapy device 4 has a treatment gantry and a treatment bed arranged in a treatment room. The treatment bed moves the top plate so that the treatment part of the patient is roughly consistent with the isocenter. The treatment gantry supports the irradiation head so that it can rotate around the rotation axis. The irradiation head irradiates radiation according to the treatment plan. Specifically, the irradiation head forms an irradiation area by a multi-segmented aperture (multi-leaf collimator), and the irradiation to normal tissue is suppressed by the irradiation field. By irradiating the treatment part with radiation, the treatment part disappears or shrinks.

[0062] The radiotherapy support device 5 is installed in a treatment room where the radiotherapy device 4 is installed or in a control room adjacent to the treatment room. The radiotherapy support device 5 is a computer that outputs guidance information for guiding work related to radiotherapy.

[0063] Hereinafter, an embodiment related to the radiation therapy planning device 3 will be described as a first embodiment, and an embodiment related to the radiation therapy supporting device 5 will be described as a second embodiment.

[0064] (First Embodiment)

[0065] Figure 2 1 is a diagram showing a configuration example of a radiation therapy planning apparatus 3 according to the first embodiment. The radiation therapy planning apparatus 3 includes a processing circuit 31 , a storage device 32 , a display device 33 , an input device 34 , and a communication device 35 .

[0066] The processing circuit 31 has a processor such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processor starts the radiation therapy planning program installed in the storage device 32, etc., thereby realizing the acquisition function 311, the condition setting function 312, the area determination function 313, the calculation function 314, the determination function 315 and the display control function 316. In addition, each function 311 to 316 is not limited to being realized by a single processing circuit. It is also possible to combine multiple independent processors to form a processing circuit, and realize each function 311 to 316 by executing the program by each processor.

[0067] The processing circuit 31 acquires various information by realizing the acquisition function 311. For example, the processing circuit 31 acquires the data of the medical image received from the medical image diagnosis apparatus 2.

[0068] By implementing the condition setting function 312, the processing circuit 31 sets the radiation irradiation conditions related to the radiation therapy. The irradiation conditions include at least an irradiation field and an irradiation dose index value. The irradiation field is an area to which the radiation is irradiated. The irradiation dose index value is a dose index value of the irradiated radiation. The dose index value includes a total dose representing the total amount of the irradiated dose and a dose rate representing the dose irradiated per unit time.

[0069] By implementing the calculation function 314, the processing circuit 31 calculates the volume index value of the area related to the predicted dose index value below the first threshold value in the normal tissue included in the irradiation field based on the irradiation conditions set by the condition setting function 312. The predicted dose index value is a dose index value calculated by the processing circuit 31 and the like when planning the radiotherapy, and is a predicted value of the dose index value irradiated to the position corresponding to each pixel of the medical image. Specifically, the predicted dose index value includes a predicted dose value as a predicted value of the total dose and a predicted dose value as a predicted value of the dose rate. The volume index value is an index value related to the volume, for example, including the volume or the volume ratio.

[0070] By implementing the determination function 315, the processing circuit 31 determines whether the irradiation condition set by the condition setting function 312 is permitted based on the volume index value calculated by the calculation function 314. More specifically, the processing circuit 31 determines that the irradiation condition is not permitted when the volume index value exceeds the second threshold value, and determines that the irradiation condition is permitted when the volume index value is lower than the second threshold value.

[0071] In the display control function 316, the processing circuit 31 displays various information on the display device 33. For example, the processing circuit 31 displays the volume index value calculated by the calculation function 314, the determination result of the determination function 315, and the like.

[0072] The storage device 32 is a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), a semiconductor storage device, etc., which stores various information. In addition to the above storage devices, the storage device 32 may also be a removable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), a flash memory, or a drive device that reads and writes various information between a semiconductor storage element, etc. In addition, the storage device 32 may also be located in another computer connected to the radiation therapy planning device 3 via a network. For example, the storage device 32 stores a treatment planning program, etc.

[0073] The display device 33 displays various information according to the display control function 316 of the processing circuit 31. As the display device 33, for example, a liquid crystal display (LCD: Liquid Crystal Display), a CRT (Cathode Ray Tube) display, an organic EL display (OELD: Organic Electro Luminescence Display), a plasma display or other arbitrary displays can be used. In addition, the display device 33 can also be a projector.

[0074] The input device 34 receives various input operations from the user, converts the received input operations into electrical signals and outputs them to the processing circuit 31. Specifically, the input device 34 can appropriately use a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, etc. The electrical signal corresponding to the input operation of the input device is output to the processing circuit 31. The input device 34 can also be a voice recognition device that converts the sound signal collected by the microphone into an instruction signal. The input device 34 can also be an input device set in other computers connected via a network or the like.

[0075] The communication device 35 is an interface for data communication with other devices included in the radiotherapy system 1. For example, the communication device 35 receives medical image data from the medical image diagnosis device 2 via the network. In addition, the communication device 35 sends treatment plan data to the radiotherapy device 4 and the radiotherapy auxiliary device 5 via the network.

[0076] Next, an operation example of the radiation therapy planning device 3 will be described. In the following description, the medical image is a three-dimensional CT image acquired by an X-ray computed tomography device.

[0077] Figure 3 FIG. 4 is a diagram showing a typical flow of treatment planning processing by the radiation therapy planning device 3. Figure 3 As shown, the processing circuit 31 first acquires a medical image of the patient by implementing the acquisition function 311 (step SA1). The anatomical structure of the patient is depicted in the medical image acquired in step SA1.

[0078] After performing step SA1, the processing circuit 31 determines the tumor, normal tissue and risk organ according to the medical image obtained in step SA1 by implementing the area determination function 313 (step SA2). Tumors are the objects of radiotherapy. Normal tissues and risk organs are normal tissues other than tumors. Risk organs are organs with particularly high radiosensitivity among normal tissues. Normal tissues are normal tissues other than risk organs. The determination method can be performed by any method. For example, it can be performed manually by the user. Specifically, it is performed in the following order. First, the processing circuit 31 displays the medical image on the display device 33. The user draws the contours that surround the tumor, normal tissue and risk organ drawn in the medical image through an input device 34 such as a mouse or a tablet pen. The processing circuit 31 determines the image area surrounded by the contour as a tumor, normal tissue or risk organ. In the case where there are multiple tumors, normal tissues and risk organs, they are determined individually.

[0079] The identification method is not limited to the above method, and may be automatically performed by image processing. For example, the processing circuit 31 may perform threshold processing and image recognition processing on the medical image to identify the tumor, normal tissue, and risk organ.

[0080] After performing step SA2, the processing circuit 31 sets the provisional irradiation conditions by implementing the condition setting function 312 (step SA3). In step SA3, the processing circuit 31 sets the irradiation field, irradiation direction, and irradiation dose index value as irradiation conditions. The irradiation field is set in the medical image. The irradiation direction is the direction of the irradiated radiation. The irradiation direction is determined by the angle of the treatment gantry of the radiotherapy device 4 around the central axis of rotation. The irradiation dose index value includes the irradiation dose and the irradiation dose rate. The irradiation dose is defined as the total dose of radiation irradiated during multiple days of radiotherapy. The irradiation dose rate is defined as the dose of radiation per unit time.

[0081] After step SA3 is performed, the processing circuit 31 determines the FLASH area and the normal irradiation area in the irradiation field set in step SA3 by implementing the area determination function 313 (step SA4). In step SA4, the processing circuit 31 determines the irradiation area for irradiating the irradiation line that depends on the penumbra as the normal irradiation area, and determines the irradiation area for irradiating the irradiation line that does not depend on the penumbra as the FLASH area based on the irradiation field set in step SA3.

[0082] Figure 4 and Figure 5 It is a diagram schematically showing the FLASH area and the normal irradiation area when the irradiation direction is "270 degrees". Figure 4 Indicates a cross section of a medical image parallel to the beam axis of radiation. Figure 5 Represents a cross section of a medical image that is orthogonal to the beam axis of the radiation. Figure 4 and Figure 5 As shown, the medical image includes a tumor region RA and a normal tissue region RB. The tumor region RA is an image region related to the tumor determined in step SA3. The normal tissue region RB is an image region related to normal tissues and / or risk organs determined in step SA3.

[0083] like Figure 4 and Figure 5 As shown, the irradiation area R1 is set to surround the tumor area RA. The area reduced by a specified distance from the irradiation area R1 is set as the FLASH area R2. The area between the irradiation area R1 and the FLASH area R2 is set as the normal irradiation area R3. The normal irradiation area R3 is an area irradiated with radiation that has passed through the aperture set in the radiotherapy device 4, that is, the penumbra. The specified distance can be arbitrarily set according to the geometric conditions of the radiotherapy device 4. The specified distance of this embodiment is assumed to be about 5 mm. The FLASH area R2 is an area that is irradiated with a straight tangent line that does not pass through the aperture set in the radiotherapy device 4, that is, radiation that does not rely on the penumbra to achieve FLASH irradiation.

[0084] As described above, FLASH irradiation is a radiation irradiation method that selectively damages tumors without damaging normal tissues by irradiating ultra-high doses of radiation in a short period of time. The effect of selectively damaging tumors without damaging normal tissues is called FLASH irradiation effect. Since the dose rate of the normal irradiation area R3 is lower than the dose rate of FLASH irradiation, the normal irradiation area R3 cannot obtain the FLASH irradiation effect, but since the radiation is irradiated at a high dose rate compared to the dose rate of normal radiotherapy, it is possible to cause excessive damage to normal tissues. Therefore, as an irradiation condition, it is appropriate that the volume of the normal tissue area RB overlapping the normal irradiation area R3 is as small as possible.

[0085] After performing step SA4, the processing circuit 31 generates a spatial distribution of the predicted dose rate related to the irradiation field determined in step SA3 by implementing the calculation function 314 (step SA5). In step SA5, the processing circuit 31 generates a spatial distribution of the predicted dose rate based on the irradiation conditions and the medical image according to an arbitrary dose calculation algorithm. The predicted dose rate is calculated as a predicted value of the administration dose rate related to one FLASH irradiation. At this time, the processing circuit 31 allocates the predicted dose rate that is reduced by the aperture to the normal irradiation area, and allocates the predicted dose rate that is not reduced by the aperture to the FLASH area, and generates a spatial distribution of the predicted dose rate. As a dose calculation algorithm, for example, an equivalent TAR (tissue-airratio) method or a differential scattering air ratio (dSAR method), a small volume method, a Monte Carlo method, a convolution method, etc. can be used.

[0086] After performing step SA5, the processing circuit 31 generates a frequency distribution (DrVH) of the predicted dose rates of the tumor, normal tissue, and risk organ determined in step SA2 by implementing the calculation function 314 (step SA6). For example, the processing circuit 31 determines the predicted dose rate assigned to each pixel of the normal tissue area corresponding to the normal tissue area and the risk organ, and calculates the volume index value of each predicted dose rate. The processing circuit 31 can generate DrVH by recording the volume index value of each predicted dose rate. As the volume index value, the volume or the volume ratio can be used. The volume can be defined as the number of pixels, or as the value obtained by multiplying the number of pixels by the volume of 1 pixel. The volume ratio is defined as the ratio of the volume of each predicted dose rate to the overall volume of the normal tissue area. In the following, it is assumed that the volume index value is the volume ratio. The processing circuit 31 can also generate DrVH for each tumor area.

[0087] After step SA6 is performed, the processing circuit 31 calculates the volume ratio less than the FLASH effect threshold by implementing the calculation function 314 (step SA7). The calculated volume ratio is called the normal irradiation volume ratio. Specifically, in step SA7, the processing circuit 31 applies the FLASH effect threshold to the DrVH of the normal tissue area generated in step SA6 to calculate the normal irradiation volume ratio.

[0088] Figure 6 is a graph showing the proportion of volume that is usually irradiated. Figure 6As shown, in step SA6, the processing circuit 31 generates a frequency distribution (DrVH) 61 of the volume ratio (Volume[%]) of the predicted dose rate (Dose_rate[Gy / s]). DrVH61 is a graph in which the horizontal axis is defined as the predicted dose rate and the vertical axis is defined as the volume ratio. Next, the processing circuit 31 sets the FLASH effect threshold Th for DrVH. The FLASH effect threshold Th is defined as the predicted dose rate at which the therapeutic effect (FLASH effect) by FLASH irradiation can be obtained. For example, the FLASH effect threshold Th is set to 40Gy / s, etc. The FLASH effect threshold Th can be set for each organ. Based on the DrVH generated in step SA6, the processing circuit 31 calculates a volume ratio 71 less than the FLASH effect threshold as the normal irradiation volume ratio. The normal irradiation volume ratio 71 refers to the volume ratio at which the FLASH effect cannot be obtained.

[0089] After performing step SA7, the processing circuit 31 determines whether the irradiation conditions set in step SA3 are within the permissible range by implementing the determination function 315 (step SA8). Specifically, the processing circuit 31 determines whether the normal irradiation volume ratio calculated in step SA7 exceeds a predetermined determination threshold. The determination threshold is, for example, set to an upper limit value of the permissible normal irradiation volume ratio. In the case where the normal irradiation volume ratio calculated in step SA7 exceeds the determination threshold, the processing circuit 31 determines that the irradiation conditions are not within the permissible range. On the other hand, in the case where the normal irradiation volume ratio calculated in step SA7 does not exceed the determination threshold, the processing circuit 31 determines that the irradiation conditions are within the permissible range.

[0090] After performing step SA8, the processing circuit 31 displays the normal irradiation volume ratio calculated in step SA7 and the determination result obtained in step SA8 (step SA9) by implementing the display control function 316. In step SA9, the processing circuit 31 displays the normal irradiation volume ratio and the determination result on the display device 33 in a prescribed layout.

[0091] Figure 7 FIG. 1 is a diagram showing an example of a display screen I1 showing a normal irradiation volume ratio and a determination result. The display screen I1 is displayed on the display device 33. Figure 7As shown, the display screen I1 includes a display area I11 of DrVH61, a display area I12 of irradiation conditions, a display area I13 of the normal irradiation area, a display area I14 of the FLASH area, and a display area I15 of the judgment result. DrVH61 is displayed in the display area I11. The normal irradiation volume ratio can also be emphasized in DrVH61. The irradiation conditions are displayed in the display area I12. The numerical value (e.g., 26%) of the volume ratio of the normal irradiation area (normal irradiation volume ratio) is displayed in the display area I13. The numerical value (e.g., 74%) of the volume ratio of the FLASH area is displayed in the display area I14. The volume ratio of the FLASH area is calculated by subtracting the normal irradiation volume ratio from 100%. A message corresponding to the judgment result of the judgment processing performed in step SA8 is displayed in the display area I15. For example, when it is determined in step SA8 that the irradiation conditions are not within the allowable range, messages such as "normal irradiation volume ratio is too much" and "please change the irradiation conditions" are displayed.

[0092] After step SA9 is performed, the processing circuit 31 determines whether to change the irradiation conditions by implementing the determination function 315 (step SA10 ).

[0093] like Figure 7 As shown, a change button I16 and an OK button I17 are displayed on the display screen I1. The change button I6 is a GUI (Graphical User Interface) button for instructing to change the irradiation conditions. The OK button I7 is a GUI button for instructing to confirm the irradiation conditions. The user observes the judgment result, the normal irradiation volume ratio, etc. displayed on the display screen I1, and when it is determined that it is better to change the irradiation conditions, the user presses the change button I16 via the input device 34, etc. When the change button I16 is pressed, the processing circuit 31 determines in step SA10 that the irradiation conditions are changed.

[0094] When it is determined in step SA10 that the irradiation condition is to be changed (step SA10: Yes), the processing circuit 31 sets a new irradiation condition by implementing the condition setting function 312 (step SA3). That is, the processing circuit 31 changes the parameter values ​​of the irradiation condition such as the irradiation field, irradiation direction, irradiation dose, and irradiation dose rate according to the instruction of the user via the input device 34 or according to a predetermined algorithm. The processing circuit 31 may change the parameter values ​​of the irradiation condition in such a way that the normal irradiation volume ratio becomes smaller, or may change the parameter values ​​of the irradiation condition in such a way that the normal irradiation volume ratio becomes smaller than the threshold value for determination. For example, the processing circuit 31 may determine a conditional expression that expresses the correspondence between the parameter values ​​of the irradiation condition and the normal irradiation volume ratio, and calculate the parameter values ​​of the irradiation condition that the normal irradiation volume ratio is the smallest based on the conditional expression. Alternatively, the processing circuit 31 may determine the parameter values ​​of the irradiation condition that the normal irradiation volume ratio can take the minimum value by using a Gaussian process regression model such as Bayesian optimization. In addition, the processing circuit 31 may randomly change the parameter values ​​of the irradiation condition. Alternatively, the processing circuit 31 may change the irradiation condition to the parameter values ​​specified by the user via the input device 34.

[0095] Figure 8 FIG. 2 is a diagram schematically showing the process of changing the irradiation conditions. Figure 8 As shown in FIG. 1 , when the irradiation direction is 270 degrees, the normal tissue region RB widely overlaps the normal irradiation region R3, and the normal irradiation volume ratio is greater than the judgment threshold, and it is judged in step SA8 that the irradiation condition is not within the allowable range. On the other hand, when the irradiation direction is 0 degrees, the normal tissue region RB overlaps the normal irradiation region R3 only in a relatively narrow range. In this case, Figure 8 As shown, the processing circuit 31 changes the irradiation direction from 270 degrees to 0 degrees.

[0096] After the irradiation conditions are changed in step SA3, the processing circuit 31 performs steps SA4-SA9 in the same manner as described above. That is, the processing circuit 31 calculates the changed volume index value based on the changed irradiation conditions, and determines whether the changed irradiation conditions are permitted based on the changed volume index value. In step SA9, the processing circuit 31 may display the normal irradiation volume ratio calculated in step SA7 based on the changed irradiation conditions and the determination result of step SA8, or may display this information together with the normal irradiation volume ratio under the irradiation conditions before the change.

[0097] Fig. 9 FIG. 1 is a diagram showing an example of a display screen I2 showing a normal irradiation volume ratio and a determination result under the irradiation conditions after the change. Fig. 9As shown, the display screen I2 includes a display area I21 of the changed DrVH62, a display area I22 of the irradiation conditions, a display area I23 of the normal irradiation area, a display area I24 of the FLASH area, a display area I25 of the determination result, a change button I26, and an OK button I27. The display area I22, the display area I23, the display area I24, the display area I25, the change button I26, and the OK button I27 are respectively Figure 7 The display area I12, display area I13, display area I14, display area I15, change button I16 and confirmation button I17 are substantially the same.

[0098] like Fig. 9 As shown, in the display area I21, DrVH62 calculated under the changed irradiation conditions and DrVH61 calculated under the irradiation conditions before the change are displayed in a curve graph. For example, the processing circuit 31 displays the changed DrVH62 and DrVH61 before the change in visual modes such as different line types and colors. By observing the changed DrVH62 and DrVH61 before the change, the user can understand the change in the normal irradiation volume ratio accompanying the change in the irradiation conditions. A message corresponding to the determination result of the determination processing performed in step SA8 is displayed in the display area I25. For example, when it is determined in step SA8 that the irradiation conditions are within the allowable range, messages such as "The normal irradiation volume ratio is small" and "The irradiation conditions are appropriate" are displayed.

[0099] After step SA9 is performed, the processing circuit 31 determines whether to change the irradiation conditions (step SA10) by implementing the determination function 315. The user observes the determination result displayed on the display screen I2, the normal irradiation volume ratio, etc., and presses the confirmation button I27 via the input device 34, etc. When the confirmation button I27 is pressed, the processing circuit 31 determines in step SA10 that the irradiation conditions are not to be changed.

[0100] When it is determined in step SA10 that the irradiation condition is not to be changed (step SA10 : No), the processing circuit 31 sets the current irradiation condition set in step SA3 as a final version by implementing the condition setting function 312 (step SA11 ).

[0101] As described above, the processing circuit 31 can search for the optimum irradiation condition in which the irradiation volume ratio is normally smaller than the determination threshold value by repeating steps SA3 to SA10 . The finalized irradiation condition is stored in the storage device 32 and sent to the radiotherapy apparatus 4 and the radiotherapy assisting apparatus 5 .

[0102] After step SA11 is performed, the treatment planning process by the radiation therapy planning apparatus 3 is completed. Then, the radiation therapy apparatus 4 irradiates the patient with radiation according to the determined irradiation conditions to perform radiation therapy.

[0103] In addition, the above Figure 3 The treatment plan processing shown is an example, and the present invention is not limited thereto, and various modifications are possible. Several modifications will be described below.

[0104] In the above processing example, it is assumed that whether or not the irradiation condition is changed is determined in step SA10. However, the present embodiment is not limited thereto. For example, the processing circuit 31 may also determine in step SA8 that the irradiation condition is not within the permissible range and regard the irradiation condition as changed. In addition, in step SA8, it may determine that the irradiation condition is within the permissible range and regard the irradiation condition as not changed.

[0105] In the above processing example, the frequency distribution (DrVH) of the predicted dose rate is generated (step SA6) and displayed (step SA9). However, the present embodiment is not limited to this. For example, the processing circuit 31 may also generate the frequency distribution (DVH) of the predicted dose for each of the FLASH area and the normal irradiation area set in step SA4, and display it on the display device 33.

[0106] Fig.10 64 is a diagram showing a display example of the DVH 64 of the FLASH area and the DVH 65 of the normal irradiation area. Fig.10 As shown, DVH64 and DVH65 are graphs in which the horizontal axis is defined as the predicted dose (Dose [Gy]) and the vertical axis is defined as the volume ratio (Volume [%). By displaying the DVH, the user can confirm the total amount of dose irradiated to the patient separately in the FLASH area and the normal irradiation area. In addition, the processing circuit 31 can also generate and display the DVH of the FLASH area and the normal irradiation area and the area. Thereby, the user can compare the DVH of the FLASH area and / or the normal irradiation area with respect to the area (all areas).

[0107] When the irradiation field includes multiple normal tissues (organs) such as the heart and stomach, the processing circuit 31 can generate and display DrVH and / or DVH for each normal tissue, or calculate and display the normal irradiation volume ratio. In this case, the processing circuit 31 can display only the DrVH and / or DVH of a specific organ, or can display multiple DrVH and / or DVH related to multiple organs. The processing circuit 31 can generate and display the DrVH and / or DVH of each organ, such as the normal irradiation volume ratio, and the normal irradiation volume ratio. Figure 6The processing circuit 31 may display the DrVH of each organ and the normal irradiation volume ratio as a curve graph as shown in the figure, or may display the DrVH of each organ and the normal irradiation volume ratio as a numerical value. By generating and displaying the DrVH of each organ or calculating and displaying the normal irradiation volume ratio, the area to which the FLASH effect is given and the area not to which the FLASH effect is given can be sorted in more detail. In addition, the processing circuit 31 may display the DrVH when all normal organs are set as a single area together with the DrVH of each organ.

[0108] As described above, the radiation therapy planning device 3 of the first embodiment includes a processing circuit 31. The processing circuit 31 sets the irradiation conditions of the radiation. The irradiation conditions include at least the irradiation field and the irradiation dose index value of the radiation set for the medical image. Based on the irradiation conditions, the processing circuit 31 calculates the volume index value of the area related to the predicted dose index value below the FLASH effect threshold in the normal tissue included in the irradiation field. The processing circuit 31 determines whether the irradiation conditions are allowed based on the volume index value.

[0109] According to the above structure, it is possible to determine whether the irradiation conditions are allowed based on the volume index value of the area in which the FLASH effect can be obtained in the normal tissue. As a result, it is possible to search for irradiation conditions in which the volume index value of the area in which the FLASH effect cannot be obtained becomes relatively small. Therefore, in ultra-high dose rate short-time irradiation methods such as FLASH irradiation, safe and high-precision radiation therapy that can reduce harmful events to normal tissues can be performed.

[0110] In addition, in the above processing example, when the volume index value of the area below the FLASH effect threshold exceeds the judgment threshold, the processing circuit 31 determines that the irradiation condition is not within the allowable range. However, the present embodiment is not limited to this. For example, the processing circuit 31 may also assume that the normal irradiation area can be regarded as an area where the FLASH effect cannot be obtained. When the volume index value of the normal irradiation area determined in step SA3 exceeds the threshold, it is determined that the irradiation condition is not within the allowable range. When the volume index value of the normal irradiation area is lower than the threshold, it is determined that the irradiation condition is within the allowable range. In this way, it is possible to simply determine whether the irradiation conditions are appropriate based on the volume index value of the foreground area where the FLASH effect is not obtained.

[0111] The processing circuit 31 of the radiotherapy planning device 3 of the first embodiment performs setting processing, acquisition processing, evaluation processing and output processing in other aspects. In the setting processing, the processing circuit 31 sets the radiation irradiation conditions for the medical image related to the patient. The irradiation conditions include the irradiation field, the total dose, the dose rate, etc., which are set by the condition setting function 312. In the acquisition processing, the processing circuit 31 obtains the histogram (DrVH) of the dose rate of the radiation in the specified area of ​​the above-mentioned patient based on the irradiation conditions. As a method of obtaining DrVH, it can be generated by the processing circuit 31 of the radiotherapy planning device 3, or it can be generated by other computers. In the latter case, the processing circuit 31 receives it from the computer that generates DrVH or the computer that stores DrVH through the communication device 35. The specified area is the irradiation field or the tumor, normal area, normal tissue and / or risk organ contained in the irradiation field. In the evaluation processing, the processing circuit 31 evaluates the irradiation conditions based on DrVH. In the output processing, the processing circuit 31 outputs information based on the evaluation result of the irradiation conditions. The information output from the processing circuit 31 may be displayed on the display device 3 , may be stored in the storage device 32 , and may be transferred to other computers via the communication device 35 .

[0112] According to the above configuration, since the irradiation conditions are evaluated based on DrVH, which is the frequency distribution of the dose rate, it is possible to easily determine whether the irradiation conditions related to the FLASH irradiation method are appropriate.

[0113] In the evaluation process, the processing circuit 31 may also determine whether the irradiation conditions are appropriate based on DrVH. Specifically, the processing circuit 31 determines whether the irradiation conditions are appropriate based on the comparison of the volume ratio of the first area (normal irradiation area) in DrVH where the irradiation effect of FLASH cannot be obtained or the second area where the irradiation effect of FLASH can be obtained in the irradiation area (FLASH area) with the first threshold (judgment threshold). Specifically, when the volume ratio of the normal irradiation area in the irradiation area is greater than the first judgment threshold, it is determined that the irradiation conditions are inappropriate, and when it is less than the first judgment threshold, it is determined that the irradiation conditions are appropriate. In addition, when the volume ratio of the FLASH area in the irradiation area is greater than the second judgment threshold, it is determined that the irradiation conditions are appropriate, and when it is less than the second judgment threshold, it is determined that the irradiation conditions are inappropriate. In addition, the processing circuit 31 may not determine whether the irradiation conditions are appropriate. For example, the processing circuit 31 may also display DrVH and the judgment threshold on the display device 33. By confirming the position of the judgment threshold in DrVH, the user can estimate the volume ratio of the normal irradiation area or the FLASH area and determine whether the irradiation conditions are appropriate.

[0114] The processing circuit 31 of the first embodiment may further perform a determination process. In the determination process, the processing circuit 31 determines a normal irradiation area and a FLASH area in a medical image or DrVH related to a predetermined area.

[0115] In the determination process, the processing circuit 31 determines the penumbra area in the specified area as the normal irradiation area, and determines the area outside the penumbra area in the specified area as the FLASH area. As an example, the processing circuit 31 determines the penumbra area and the non-penumbra area through the operator's area designation of the specified area in the medical image. As another example, the processing circuit 31 determines the penumbra area through the operator's area designation of the specified area in the medical image, and determines the area outside the penumbra area in the specified area as the non-penumbra area. As another example, the processing circuit 31 determines the non-penumbra area through the operator's area designation of the specified area in the medical image, and determines the area outside the non-penumbra area in the specified area as the penumbra area. As another example, the processing circuit 31 may also determine the determination area and the non-penumbra area from the specified area of ​​the medical image based on the parameters of the specified irradiation area.

[0116] In the determination process, the processing circuit 31 may also determine the normal irradiation area and the FLASH area based on at least one of the irradiation depth of the radiation in the irradiation area, the radiation absorption characteristics of the tissue in the irradiation area, and the penumbra in the irradiation area. The irradiation depth refers to the distance from the body surface along the irradiation direction of the radiation. Specifically, the processing circuit 31 determines the penumbra area and the non-penumbra area in the irradiation area of ​​the medical image by the above method. Next, the processing circuit 31 calculates the predicted dose rate for each pixel in the irradiation area based on the irradiation conditions. At this time, the processing circuit 31 calculates the predicted dose rate for the penumbra area by considering the attenuation of the radiation corresponding to the penumbra. In addition, the processing circuit 31 calculates the predicted dose rate by considering at least one of the attenuation rate of the radiation and the attenuation rate of the radiation corresponding to the radiation absorption characteristics of the tissue according to the irradiation depth of the radiation in the irradiation area. According to the irradiation depth, the attenuation rate of the radiation and the radiation absorption characteristics of the tissue can use experimentally determined values ​​or values ​​obtained by predictive calculation. The processing circuit 31 identifies the area where the predicted dose rate is lower than the FLASH effect threshold as the normal irradiation area, and identifies the area where the predicted dose rate is higher than the FLASH effect threshold as the FLASH area.

[0117] In the determination process, the processing circuit 31 may also determine the normal irradiation area and the FLASH area in DrVH based on the DrVH and the FLASH effect threshold. As an example, the processing circuit 31 identifies the area in DrVH where the predicted dose rate is lower than the FLASH effect threshold as the normal irradiation area, and identifies the area in DrVH where the predicted dose rate is higher than the FLASH effect threshold as the FLASH area. In this case, it is not necessary to determine the normal irradiation area and the FLASH area in the medical image.

[0118] In the determination process, the processing circuit 31 may also determine whether the irradiation conditions are appropriate based on the comparison between the predicted dose for the tissue in the normal irradiation area and the durable dose of the tissue. As an example, the determination of whether the irradiation conditions using the durable dose are appropriate is performed when it is determined that the irradiation conditions are suitable for use in the determination of whether the irradiation conditions using DrVH are appropriate. The durable dose is a dose that can withstand the irradiation of radiation. The durable dose is different for each tissue. As an example, the processing circuit 31 determines the durable dose of the tissue located in the normal irradiation area using a durable dose table. The durable dose table is a LUT (Look Up Table) that records the durable dose for each category of the tissue. The category of the tissue means the anatomical name or symbol of the tissue. The processing circuit 31 determines the category of the tissue located in the normal irradiation area using anatomical landmarks, etc., searches the durable dose table using the determined category of the tissue as a search keyword, and determines the durable dose of the tissue. On the other hand, the processing circuit 31 generates a spatial distribution of the predicted dose. The processing circuit 31 determines the tissue of the treatment object in the normal irradiation area, determines the predicted dose of the tissue with reference to the spatial distribution of the predicted dose, and compares the determined predicted dose with the durable dose of the tissue. When the predicted dose exceeds the durable dose, the irradiation condition is determined to be inappropriate, and when the predicted dose is lower than the durable dose, the irradiation condition is determined to be appropriate. According to this determination process, not only the volume ratio of the normal irradiation area and / or the FLASH area but also the durable dose is used to determine whether the irradiation condition is appropriate, thereby further reducing unnecessary radiation to normal tissues and the like. In addition, the determination of whether the irradiation condition is appropriate using the durable dose can also be performed instead of the determination of whether the irradiation condition is appropriate using the DrVH.

[0119] In the output process, the processing circuit 31 displays information based on whether the irradiation conditions are appropriate on the display device 33. The information based on whether the irradiation conditions are appropriate may be information indicating that the irradiation conditions are appropriate or information indicating that the irradiation conditions are inappropriate, or may be information urging the start of radiotherapy based on the appropriateness of the irradiation conditions or information urging the change of the irradiation conditions based on the inappropriateness of the irradiation conditions. As an example, the information indicating that the irradiation conditions are appropriate is displayed on the display device 33. Fig. 9The information urging the change of irradiation conditions is listed as follows: Figure 7 "The normal irradiation volume ratio is high. Please change the irradiation conditions." in the display column I15.

[0120] In the output process, the processing circuit 31 displays the normal irradiation area and the FLASH area on the display device 33 so that they can be distinguished. As an example, the processing circuit 31 Figure 7 As shown, the normal irradiation area (area drawn with diagonal lines) and the FLASH area (area drawn with blank spaces) are visually distinguished in the DrVH. At this time, the processing circuit 31 may add a mark indicating the judgment threshold to the DrVH. As an example, the display indicates Figure 7 As another example, the processing circuit 31 may visually distinguish and display the normal irradiation area and the FLASH area in the medical image.

[0121] In the output process, the processing circuit 31 may also display a numerical value representing the volume ratio of the normal irradiation area and / or the FLASH area on the display device 33. For example, Figure 7 As shown, the processing circuit 31 can display both the numerical value "26%" indicating the volume ratio of the normal irradiation area and the numerical value "74%" indicating the volume ratio of the FLASH area.

[0122] (Second Embodiment)

[0123] Fig.11 1 is a diagram showing a configuration example of a radiotherapy supporting device 5 according to the second embodiment. The radiotherapy supporting device 5 includes a processing circuit 51 , a storage device 52 , a display device 53 , an input device 54 , and a communication device 55 .

[0124] The processing circuit 51 has a processor such as a CPU and a GPU. The processor starts the radiation therapy planning program installed in the storage device 32, etc., thereby realizing the acquisition function 511, the calculation function 512, the distribution display function 513, the determination function 514 and the warning function 515. In addition, each function 511-515 is not limited to the case where it is realized by a single processing circuit. It is also possible to combine multiple independent processors to form a processing circuit, and realize each function 511-515 by executing the program by each processor.

[0125] The processing circuit 51 acquires various information by realizing the acquisition function 511. For example, the processing circuit 51 acquires data of the predicted dose rate frequency distribution (DrVH) and the normal irradiation volume ratio received from the radiation therapy planning device 3.

[0126] By implementing the calculation function 512, the processing circuit 51 calculates the positional deviation of the patient placed on the treatment bed of the radiotherapy apparatus 4. Specifically, the processing circuit 51 calculates the positional deviation between the current position of the patient placed on the treatment bed of the radiotherapy apparatus 4 and the reference position.

[0127] The processing circuit 51 displays the frequency distribution of the predicted dose index value (DrVH) related to the current position and the frequency distribution of the predicted dose index value (DrVH) related to the reference position by implementing the distribution display function 513. For example, the processing circuit 51 displays the DrVH related to the current position and the DrVH related to the reference position on the display device 53.

[0128] By implementing the determination function 514, the processing circuit 51 determines whether the position offset calculated by the calculation function 512 is allowed based on the comparison between the volume index value of the area related to the predicted dose index value below the first threshold in the normal tissue of the patient corresponding to the current position and the reference volume index value. The reference volume index value is the volume index value of the area related to the predicted dose index value below the first threshold in the normal tissue of the patient corresponding to the reference position. As the volume index value of the area related to the predicted dose index value below the first threshold, the normal irradiation volume ratio of the first embodiment can be used. The first threshold is set to the FLASH effect threshold of the first embodiment.

[0129] By implementing the warning function 515, the processing circuit 51 issues a warning when the determination function 514 determines that the positional deviation is not permitted. The warning may be issued as a warning message via the display device 53 or as a warning sound via a speaker.

[0130] The storage device 52 is a storage device such as a ROM or RAM, HDD, SSD, integrated circuit storage device, etc. that stores various information. In addition to the above storage devices, the storage device 52 may also be a drive device that reads and writes various information between removable storage media such as CD, DVD, flash memory, semiconductor storage elements, etc. In addition, the storage device 52 may also be located in another computer connected to the radiotherapy assisting device 5 via a network. For example, the storage device 52 stores a treatment assisting program, etc.

[0131] The display device 53 displays various information. For example, a liquid crystal display, a CRT display, an organic EL display, a plasma display, or any other display can be used as appropriate as the display device 53. In addition, the display device 53 may also be a projector.

[0132] The input device 54 receives various input operations from the user, converts the received input operations into electrical signals and outputs them to the processing circuit 51. Specifically, the input device 54 can appropriately use a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, etc. The electrical signal corresponding to the input operation of the input device is output to the processing circuit 51. The input device 54 can also be a voice recognition device that converts the sound signal collected by the microphone into an instruction signal. The input device 54 can also be an input device set in other computers connected via a network or the like.

[0133] The communication device 55 is an interface for performing data communication with other devices included in the radiotherapy system 1. For example, the communication device 55 acquires data of a predicted dose rate frequency distribution (DrVH) and a normal irradiation volume ratio received from the radiotherapy planning device 3.

[0134] Next, an operation example of the radiotherapy support device 5 will be described. In the following description, it is assumed that the medical image is a three-dimensional medical image acquired by an X-ray computed tomography device.

[0135] Fig.12 It is a diagram showing a typical flow of treatment support processing by the radiation treatment support device 5 .

[0136] like Fig.12 As shown, the processing circuit 51 calculates the position offset of the patient by implementing the position offset calculation function 512 (step SB1). In step SB1, the processing circuit 51 calculates the position offset between the current position of the patient and the reference position. The current position of the patient can be obtained by any method. For example, the user optically scans the patient placed on the bed using a shape measuring device that applies three-dimensional optical scanning. The shape measuring device generates a graphic model related to the appearance of the patient (hereinafter referred to as the patient model) based on a series of data of position information of the sample points, that is, scan data. The patient model at the current position is stored in the storage device 52 of the radiotherapy auxiliary device 5. On the other hand, the storage device 52 stores a patient model of a reference position generated in advance. The reference position is the position of the patient at the time of treatment planning. That is, the reference position is, for example, the position of the patient when the medical image used for treatment planning is collected.

[0137] The processing circuit 51 arranges the patient model at the current position and the patient model at the reference position in the same image processing coordinate system, and calculates the positional offset between the patient model at the current position and the patient model at the reference position. The positional offset is specified by a combination of a direction (hereinafter referred to as the positional offset direction) and a distance (hereinafter referred to as the positional offset amount). The positional offset direction is represented, for example, by the head-to-tail direction, the left-right direction, and the front-to-back direction of the patient. The positional offset amount is specified as the distance from the reference position. The calculation of the positional offset is specifically performed as follows. First, the processing circuit 51 determines the same anatomical reference of the patient model at the current position and the patient model at the reference position, and then calculates the positional offset direction and the positional offset amount from the anatomical reference of the patient model at the reference position to the anatomical reference of the patient model at the current position.

[0138] After performing step SB1, the processing circuit 51 determines whether there is a position offset by implementing the position offset calculation function 512 (step SB2). In step SB2, the processing circuit 51 compares the position offset calculated in step SB1 with a threshold. The threshold can be set to any value such as 0. When the position offset is lower than the threshold, the processing circuit 51 determines that there is no position offset (step SB2: No). At this time, Fig.12 The treatment support process shown ends. When the positional deviation exceeds the threshold value, the processing circuit 51 determines that there is a positional deviation.

[0139] When it is determined in step SB2 that there is a positional deviation (step SB2: Yes), the processing circuit 51 acquires the frequency distribution of the predicted dose rate (DrVH) corresponding to the current position and the frequency distribution of the predicted dose rate (DrVH) at the reference position by implementing the acquisition function 511 (step SB3).

[0140] Fig.13 FIG. 2 is a diagram schematically showing a series of processes related to obtaining the DrVH at the current position and the DrVH at the reference position. Fig.13 As shown in FIG. 1 , the reference position and current position of the patient are obtained. The current position is set to be offset 3 cm in the caudal direction from the reference position. In step SB1, the position offset between the reference position and the current position is calculated. Fig.13 In the case of , the position offset direction is the tail direction, and the position offset amount is 3 cm.

[0141] In step SB3, for each of the plurality of combinations of the position shift direction and the position shift amount, DrVH is associated with the normal irradiation volume ratio and stored in the storage device 32. For each of the plurality of combinations, DrVH and the normal irradiation volume ratio are generated and calculated in advance by the radiation therapy planning device 3. For example, the processing circuit 31 of the radiation therapy planning device 3 generates and calculates DrVH and the normal irradiation volume ratio when the patient's organs are shifted at predetermined intervals in the head-to-tail direction, the left-right direction, and the front-to-back direction with the reference position as the center. DrVH and the normal irradiation volume ratio are generated and calculated according to the irradiation conditions of the determined version.

[0142] like Fig.13 As shown in FIG. 1 , when it is determined in step SB2 that there is a positional deviation, DrVH of the reference position and DrVH of the current position are acquired from the storage device 52. Fig.13 In the case of , the DrVH at the position 3 cm in the tail direction from the reference position is obtained as the DrVH at the current position.

[0143] After step SB3, the processing circuit 51 displays the DrVH at the current position and the DrVH at the reference position obtained in step SB3 by implementing the distribution display function 513 (step SB4). In step SB4, the processing circuit 51 displays the DrVH at the current position and the DrVH at the reference position on the display device 53 in a prescribed layout.

[0144] Fig.14 1 is a diagram showing an example of a display screen I3 showing DrVH at the current position and DrVH at the reference position. The display screen I3 is displayed on the display device 53. Fig.14 As shown, the display screen I3 includes a display area 31 for DrVH and a display area I32 for messages. In the display area I31, DrVH71 of the current position and DrVH72 of the reference position are displayed. By displaying DrVH71 of the current position and DrVH72 of the reference position, the user can infer the damage caused by radiation at a dose rate less than the FLASH effect threshold to the normal tissue at the current position compared with the reference position. DrVH71 of the current position and DrVH72 of the reference position are displayed in different visual forms such as line types or colors. In the display area I32, a message corresponding to the determination result of whether there is a positional shift in step SB2 is displayed. For example, in a case where it is determined in step SB2 that there is a positional shift, as shown in FIG. Fig.14 As shown, a message indicating positional deviation such as "positional deviation has occurred" is displayed.

[0145] After step SB4 is performed, the processing circuit 51 obtains the normal irradiation volume ratio of the current position and the normal irradiation volume ratio of the reference position by implementing the acquisition function 511 (step SB5). In step SB5, the processing circuit 51 obtains the normal irradiation volume ratio of the current position and the normal irradiation volume ratio of the reference position from the storage device 52 storing the normal irradiation volume ratios of each of a plurality of combinations of position offset directions and position offset amounts.

[0146] After step SB5 is performed, the processing circuit 51 determines whether the position deviation calculated in step SB1 is outside the allowable range by implementing the determination function 514 (step SB6). In step SB6, the processing circuit 51 determines that the position deviation is outside the allowable range when the position deviation exceeds a predetermined threshold value, and determines that the position deviation is not outside the allowable range when the position deviation is below a predetermined threshold value. The threshold value can be set to any value. In addition, the threshold value can also be set to different values ​​depending on the position deviation direction.

[0147] If it is determined in step SB6 that the positional deviation is outside the permissible range (step SB6: Yes), the processing circuit 51 issues a warning by implementing the warning function 515 (step S7). In step SB7, the processing circuit 51 displays a warning screen on the display device 53 in a predetermined layout.

[0148] Fig.15 1 is a diagram showing an example of a warning screen I4. The warning screen I4 is displayed on the display device 53. Fig.15 As shown, the warning screen I4 includes a display area I41 of DrVH, a first display area I42, a second display area I43 and a third display area I44. The display area I41 of DrVH and the first display area I42 are respectively Fig.14 The display area I31 and the display area I32 are the same.

[0149] like Fig.15 As shown, a message corresponding to the result of determination whether the position offset in step SB6 is outside the allowable range is displayed in the second display area I43. For example, when it is determined in step SB6 that the position offset is outside the allowable range, a warning message such as "position offset is not allowed" is displayed. Information indicating the correction direction and correction amount of the position offset is displayed in the third display area I44. The correction direction and correction amount of the position offset are calculated based on the position offset direction and position offset amount from the reference position to the current position calculated in step SB1. Specifically, the correction direction of the position offset is defined as the position offset direction from the current position to the reference position, and the correction amount is defined as the position offset amount from the current position to the reference position. For example, Fig.13As shown, when the positional deviation from the reference position to the current position is 3 cm in the caudal direction, the correction direction is the cranial direction and the correction amount is 3 cm. By displaying the correction direction and correction amount in this way, the user can easily place the patient from the current position to the reference position.

[0150] In addition, the correction direction and correction amount are not limited to Fig.15 For example, if a projector can be used as the display device 53, the correction direction and correction amount can be projected onto the patient's body surface.

[0151] Fig.16 is a diagram showing a projection example of the correction direction and correction amount. Fig.16 As shown in FIG. 4 , a patient P is placed on a bed 41 of the radiotherapy device 4. Fig.12 As shown, it is placed at the current position which is offset 3cm from the reference position in the caudal direction. In this case, the correction direction and the correction amount are, as described above, the head direction and 3cm, respectively. The projector as the display device 53 projects a projection image I5 representing the correction direction and the correction amount onto the body surface of the patient P. The projection image I5 is composed of a mark representing the correction direction and a numerical value representing the correction amount. Specifically, as a mark representing the correction direction, an arrow representing the head direction is projected, and numerical values ​​such as 3cm representing the correction amount are overlapped and projected on the arrow. In this way, by projecting the correction direction and the correction amount onto the patient's body surface, the user can grasp the correction direction and the correction amount without moving the line of sight to the display.

[0152] After step SB7 is performed, the treatment support process by the radiotherapy support device 5 is completed. After the treatment support process, the radiotherapy device 4 performs radiotherapy on the patient.

[0153] In addition, the above Fig.12 The treatment support process shown is an example, but is not limited thereto, and various modifications are possible. Several modifications will be described below.

[0154] In the above-described processing example, the processing circuit 51 acquires DrVH in step SB3 and displays DrVH in step SB4 . However, the processing circuit 51 may acquire DVH in step SB3 and display DVH in step SB4 .

[0155] As described above, the radiotherapy auxiliary device 5 of the second embodiment includes a processing circuit 51. The processing circuit 51 calculates the positional offset between the current position of the patient placed on the bed of the radiotherapy device 4 and the reference position. The processing circuit 51 determines whether the positional offset is allowed based on a comparison between the volume index value (usually the irradiation volume ratio) of the area related to the predicted dose index value below the FLASH effect threshold in the normal tissue of the patient corresponding to the current position and the reference volume index value. When the processing circuit 51 determines that the positional offset is not allowed, it issues a warning.

[0156] According to the above configuration, the processing circuit 51 determines whether the patient position shift is permissible based on the normal irradiation volume ratio of normal tissue, and thus can evaluate the appropriateness of the patient position shift corresponding to the volume amount for obtaining the FLASH effect on normal tissue.

[0157] According to at least one of the embodiments described above, it is possible to reduce harmful events to normal tissues during radiation therapy.

[0158] The term "processor" used in the above description refers to circuits such as CPU, GPU, or application-specific integrated circuit (ASIC), programmable logic device (for example, simple programmable logic device (SPLD), complex programmable logic device (CPLD), and field programmable gate array (FPGA)). The processor implements its functions by reading and executing the program stored in the storage circuit. In addition, it can also be configured to directly load the program into the circuit of the processor instead of storing the program in the storage circuit. In this case, the processor implements its functions by reading and executing the program loaded into the circuit. In addition, it is also possible not to execute the program, but to implement the function corresponding to the program by a combination of logic circuits. In addition, the processors of the present embodiment are not limited to the case where each processor is configured as a single circuit, and multiple independent circuits can be combined to form a processor to implement its functions. Furthermore, it is also possible to Figure 1 , Figure 2 as well as Fig.11 Multiple components in a processor are combined into one to realize its functions.

[0159] Several embodiments are described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, changes, and combinations of embodiments can be performed without departing from the scope of the invention. These embodiments or their variations are included in the scope or spirit of the invention, and are also included in the invention described in the claims and their equivalents.

[0160] Regarding the above-mentioned embodiment, the following supplementary notes are disclosed as one aspect and optional features of the invention.

[0161] (Note 1)

[0162] A radiation therapy planning device includes a processing circuit, which performs the following processing:

[0163] Setting radiation exposure conditions for medical images related to patients,

[0164] Based on the irradiation conditions, a histogram of the radiation dose rate in a predetermined area of ​​the patient is obtained;

[0165] Based on the histogram, the irradiation conditions are evaluated.

[0166] Information based on the evaluation result of the irradiation conditions is output.

[0167] (Note 2)

[0168] The processing circuit may determine whether the irradiation condition is appropriate based on the histogram.

[0169] (Note 3)

[0170] Alternatively, the processing circuit determines whether the irradiation condition is appropriate based on a comparison of a volume ratio of the first area in the histogram that cannot obtain the FLASH-based irradiation effect or the second area that can obtain the FLASH-based irradiation effect in the irradiation area with a first threshold value. FLASH irradiation is a method of selectively damaging tumors without damaging normal tissues by irradiating ultra-high dose rate (e.g., 40 Gy / sec or more) radiation in a short time (e.g., less than 1 sec).

[0171] (Note 4)

[0172] The processing circuit determines the first region and the second region in the medical image or the histogram related to the prescribed region.

[0173] (Note 5)

[0174] Alternatively, the processing circuit may determine a penumbra region in the predetermined area as the first area, and determine an area other than the penumbra region in the predetermined area as the second area.

[0175] (Note 6)

[0176] The processing circuit may determine the first region and the second region based on at least one of an irradiation depth of radiation in the irradiation region, a radiation absorption characteristic of a tissue in the irradiation region, and a penumbra in the irradiation region.

[0177] (Note 7)

[0178] The processing circuit determines the first region and the second region based on the histogram and a second threshold related to the dose rate.

[0179] (Note 8)

[0180] The processing circuit may determine whether the irradiation condition is appropriate based on a comparison between a predicted dose for tissue present in the first region where the irradiation effect by FLASH cannot be obtained and a durable dose of the tissue.

[0181] (Note 9)

[0182] Alternatively, the processing circuit may display information on whether the illumination condition is appropriate on a display device.

[0183] (Note 10)

[0184] When the processing circuit determines that the irradiation condition is inappropriate, the processing circuit may display information urging a change in the irradiation condition as information based on whether the irradiation condition is appropriate.

[0185] (Note 11)

[0186] Alternatively, the processing circuit displays the first area and the second area on a display device in a identifiable manner.

[0187] (Note 12)

[0188] Alternatively, the processing circuit displays the first region and the second region in the histogram on a display device in a visually distinguishable manner.

[0189] (Note 13)

[0190] The processing circuit may add a mark indicating the first threshold value to the displayed histogram.

[0191] (Note 14)

[0192] Alternatively, the processing circuit displays a numerical value representing a volume ratio of the first region and / or the second region on a display device.

[0193] (Note 15)

[0194] A radiation therapy planning method comprises the following steps:

[0195] Setting radiation exposure conditions for medical images related to patients,

[0196] Based on the irradiation conditions, a histogram of the radiation dose rate in a predetermined area of ​​the patient is obtained;

[0197] Based on the histogram, the irradiation conditions are evaluated.

[0198] Information based on the evaluation result of the irradiation conditions is output.

[0199] (Note 16)

[0200] A radiotherapy assisting device is provided with a processing circuit, which performs the following processing:

[0201] Calculate the positional deviation between the current position of the patient placed on the bed and the reference position,

[0202] determining whether the position shift is permitted based on a comparison between a volume ratio of a region associated with a predicted dose rate below a threshold value in normal tissue of the patient corresponding to the current position and a reference value,

[0203] If it is determined that the positional deviation is not permissible, a warning is issued.

[0204] (Note 17)

[0205] The reference value may be a volume ratio of a region associated with a predicted dose rate lower than the threshold value in the normal tissue of the patient corresponding to the reference position.

[0206] (Note 18)

[0207] The processing circuit displays a first histogram of predicted dose rates associated with the current position and a second histogram of predicted dose rates associated with the reference position on a display device.

[0208] (Note 19)

[0209] A radiation therapy planning device includes a processing circuit, which performs the following processing:

[0210] Setting radiation exposure conditions,

[0211] Based on the irradiation conditions, calculating a volume index value of a region associated with a predicted dose index value below a first threshold,

[0212] Whether the irradiation condition is permitted is determined based on the volume index value.

[0213] The irradiation conditions include at least an irradiation field and an irradiation dose index value of radiation set for the medical image.

[0214] (Note 20)

[0215] The processing circuit may determine that the irradiation condition is not permitted when the volume index value is greater than a second threshold value, and determine that the irradiation condition is permitted when the volume index value is less than the second threshold value.

[0216] (Note 21)

[0217] Alternatively, the processing circuit generates a spatial distribution of predicted dose index values ​​related to the irradiation field based on the irradiation conditions, generates a frequency distribution of predicted dose index values ​​related to the normal tissue based on the spatial distribution, and applies the first threshold to the frequency distribution to calculate the volume index value.

[0218] (Note 22)

[0219] Alternatively, the device may further include an area determination unit that determines, from the irradiation field, a first irradiation area to be irradiated with radiation that depends on the penumbra and a second irradiation area to be irradiated with radiation that does not depend on the penumbra. The calculation unit may also assign a predicted dose index value that is reduced by the aperture to the first irradiation area and a predicted dose index value that is not reduced by the aperture to the second irradiation area to generate the spatial distribution.

[0220] (Note 23)

[0221] The radiation therapy planning apparatus may further include a display device that displays the volume index value as a numerical value or a graph.

[0222] (Note 24)

[0223] The radiation therapy planning apparatus may further include a display device configured to display the volume index value related to the first irradiation field and the volume index value related to the second irradiation field in the form of numerical values ​​or graphs.

[0224] (Note 25)

[0225] Alternatively, when the processing circuit determines that the irradiation condition is not permitted, the processing circuit changes the irradiation condition according to the operator's instruction or according to a predetermined algorithm. Alternatively, the processing circuit calculates a changed volume index value based on the changed irradiation condition. Alternatively, the processing circuit determines whether the changed irradiation condition is permitted based on the changed volume index value.

[0226] (Note 26)

[0227] The irradiation conditions may also include an irradiation direction of the radiation.

[0228] (Note 27)

[0229] The first threshold may have a value capable of obtaining a therapeutic effect by high-dose ultra-short-time irradiation on the normal tissue.

[0230] (Note 28)

[0231] Alternatively, when the irradiation field includes a plurality of normal tissues, the processing circuit may calculate the volume index value for each of the plurality of normal tissues.

[0232] (Note 29)

[0233] Alternatively, the predicted dose index value is a predicted dose value and / or a predicted dose rate value. Alternatively, the volume index value is a volume or a volume ratio.

[0234] (Note 30)

[0235] A radiotherapy assisting device is provided with a processing circuit, which performs the following processing:

[0236] Calculate the positional deviation between the current position of the patient placed on the bed and the reference position,

[0237] determining whether the position shift is permitted based on a comparison between a volume index value of a region associated with a predicted dose index value below a threshold value in normal tissue of the patient corresponding to the current position and a reference volume index value,

[0238] If it is determined that the positional deviation is not permissible, a warning is issued.

[0239] (Note 31)

[0240] The reference volume index value may be a volume index value of a region associated with a predicted dose index value lower than the threshold value in the normal tissue of the patient corresponding to the reference position.

[0241] (Note 32)

[0242] The radiotherapy supporting apparatus may further include a display device configured to display a first frequency distribution of predicted dose index values ​​associated with the current position and a second frequency distribution of predicted dose index values ​​associated with the reference position.

[0243] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope or subject matter of the invention, and are included in the invention described in the claims and the scope of their equivalents.

Claims

1. A radiation therapy planning device, comprising a processing circuit, which performs the following processing: setting radiation irradiation conditions for a medical image related to a patient, obtaining a histogram of the radiation dose rate in a specified area of ​​the patient based on the irradiation conditions, evaluating the irradiation conditions based on the histogram, and outputting information based on the evaluation results of the irradiation conditions.

2. The radiation therapy planning apparatus according to claim 1, wherein: The processing circuit determines whether the irradiation condition is appropriate based on the histogram.

3. The radiation therapy planning apparatus according to claim 2, wherein: The processing circuit determines whether the irradiation conditions are appropriate based on a comparison of the volume ratio of the first area in the histogram that cannot obtain the irradiation effect based on FLASH, i.e., ultra-high dose rate short-time irradiation method, or the second area that can obtain the irradiation effect based on FLASH, in the specified area with a first threshold.

4. The radiation therapy planning apparatus according to claim 3, wherein: The processing circuit determines the first region and the second region in the medical image or the histogram related to the prescribed region.

5. The radiation therapy planning apparatus according to claim 4, wherein: The processing circuit determines a penumbra region in the prescribed area as the first area, and determines an area other than the penumbra region in the prescribed area as the second area.

6. The radiation therapy planning apparatus according to claim 4, wherein: The processing circuit determines the first region and the second region based on at least one of an irradiation depth of radiation in the prescribed region, a radiation absorption characteristic of a tissue in the prescribed region, and a penumbra in the prescribed region.

7. The radiation therapy planning apparatus according to claim 4, wherein: The processing circuit determines the first region and the second region based on the histogram and a second threshold related to the dose rate.

8. The radiation therapy planning apparatus according to claim 2, wherein: The processing circuit determines whether the irradiation condition is appropriate based on a comparison between a predicted dose for the tissue existing in a first region where the irradiation effect by FLASH cannot be obtained and a durable dose of the tissue.

9. The radiation therapy planning apparatus according to claim 2, wherein: The processing circuit displays information based on whether the illumination condition is appropriate on a display device.

10. The radiation therapy planning apparatus according to claim 9, wherein: When the processing circuit determines that the irradiation condition is inappropriate, the processing circuit displays information urging the user to change the irradiation condition as information based on whether the irradiation condition is appropriate.

11. The radiation therapy planning apparatus according to claim 3, wherein: The processing circuit displays the first area and the second area identifiably on a display device.

12. The radiation therapy planning apparatus according to claim 3, wherein: The processing circuit displays the first region and the second region in the histogram visually distinguishable on a display device.

13. The radiation therapy planning apparatus according to claim 12, wherein: The processing circuit adds a mark indicating the first threshold value to the displayed histogram.

14. The radiation therapy planning apparatus according to claim 3, wherein: The processing circuit displays a numerical value representing a volume ratio of the first region and / or the second region on a display device.

15. A radiation therapy planning method, comprising the following steps: setting radiation irradiation conditions for a medical image related to a patient, obtaining a histogram of the radiation dose rate in a specified area of ​​the patient based on the irradiation conditions, evaluating the irradiation conditions based on the histogram, and outputting information based on the evaluation results of the irradiation conditions.

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